What is a halo nevus?
A halo nevus is a mole surrounded by a white ring or halo. These moles are almost always benign, meaning they aren’t cancerous. Halo nevi (the plural of nevus) are sometimes called Sutton nevi or leukoderma acquisitum centrifugum. They’re fairly common in both children and young adults.
Keep reading to learn more about what causes them and when you should see a healthcare provider.
What does it look like?
Halo nevi look like regular brown, tan, or pink moles in the center of a circular white patch of skin. They can show up anywhere on the body, but they’re most common on your chest, abdomen, and back.
Your halo nevus may look different depending on how long you’ve had it. Halo nevi are categorized into four stages, based on how old they are. You may have multiple halo nevi at different stages of development.
The stages include:
- Stage 1. A circular ring of pale skin surrounds a mole.
- Stage 2. The mole begins to fade or becomes pinker, then fades away.
- Stage 3. A circular or oval area of white skin persists after the mole disappears.
- Stage 4. The white patch gradually returns to its normal color.
What causes them?
Halo nevi develop when your body’s immune system attacks a mole. Researchers aren’t sure why this happens, but it’s likely because your immune system thinks the mole is harmful in some way. As extra protection, white blood cells called T cells attack the pigment cells in the mole, causing it to fade and eventually disappear. They also attack the pigment surrounding the mole, creating the distinctive white outline that halo nevi are known for.
In other cases, a sunburn damages an existing mole, which leads your immune system to treat it as a harmful invader.
Can they be cancerous?
Halo nevi are almost always benign. In rare cases, however, a halo nevus can indicate the presence of melanoma, a form of skin cancer, somewhere else on the body. This is more likelyto be the case in older adults and those with halo nevi that are irregularly shaped or colored.
It’s important to keep track of any unusual moles. Changes in the color or size can indicate melanoma. When tracking your moles, keep the ABCDE rule in mind:
- Asymmetry. The shape of one half does not match the other.
- Border. The edges are often undefined, ragged, notched, or blurred. Color can bleed out into the surrounding skin.
- Color. Multiple shades of black, brown, or tan are visible. You may also see areas of white, gray, red, pink, or blue.
- Diameter. There is a change in size, usually an increase.
- Evolving. The mole has changed over the past few weeks or months.
How are they diagnosed?
In many cases, your doctor can diagnose a halo nevus just by looking at it. If you have a higher risk of skin cancer, due to family history, for example, they may do a biopsy. This involves removing all or part of the mole and checking it for cancer cells. Biopsy is the only way to diagnose, or rule out, melanoma.
How are they treated?
Halo nevi don’t require any treatment. It may take a while, but a halo nevus will eventually fade away on its own, and your skin pigmentation should return to its usual color.
Make sure you apply sunscreen to your halo nevus whenever you’re outside for more than 15 minutes. The lack of pigment around the mole leaves your skin more vulnerable to sunburns, which can increase your risk of skin cancer.